Distillation of oil



May 21,1929. A. E'. MILLER DISTILLATION OF OIL Filed June l1, 1927 wPSK@- Patented May 21, 1929.

UNITED STATESg PATENT OFFICE.

ALBERT E. MILLER, 0F WililSlIEIELD, NEW JERSEY, ASSIGNOR T0 SINCLAIRREFINING COMPANY, OF NEW YORK, N. Y., A CORPORATION 0F MAINE. i

DISTILLATION 0F OIL.

Application led June 11,

This invention relates to improvements in the distlllation of heavypetroleum-distillates Land residues for the production of lighter oils,particularly gasoline, therefrom. The invention-includes improvements inapparatus as well as improvements in process.

' In carrying"\out the process of the invention, heavy petroleumdistillates or residues are heated and distilled while in intimatecontact with fullers earth. The heated body of oil undergoingdistillation is maintained at a temperature between about 575 F. and 650F. The distillation is carried out under substantially atmosphericpressure. The g oil supplied to the distillation is, with advantage,stripped of any light components it may contain. A body of fullers earthsubstantially coextensive with the heated body of oil is maintained incontact therewith during the heating and distillation.

At temperatures between about 575 F. and 650 F. fullers earth apparentlyhas a catalytic action upon petroleum oils7 which promotes reactionsproducing lighter oils of a gasoline character therefrom. At lowertemperatures this action seems to be inconsequential in extent if ittakes place at all. At higher temperatures decomposition asian effect ofheat alone begins to be substantial in extent and, unless the operationis otherwise controlled, as for example by the imposition ofsuperatmospheric pressures, heavier oils tend to escape by vaporizationWithout the desired production of lighter oils. Operation undersubstantially atmospheric pressure is one of the advantages of thisinvention;

Another advantage of the invention is the maintenance of intimatecontact between the ullers earth and the oil undergoing distillation foramaximum period of time. This intimate contact between earth and oil fora maximum period 'of time is promoted by maintaining the earth body incontact with the oil substantially coextensive therewith and also bykeeping the heavy oil supplied to the operation free from any largeamount of light components -vaporizing rapidly at the operatingtemperature. It is advantageous to keep the oil supplied to theoperation substantially free from such light components, at least frommore than a minor proportion of such components.

Although the body of Jfullers earth is maintained substantiallycoextensive with the body ofoil undergoing distillation7 the body ofearth is maintained free from contact with 1927. Serial N0. 198,124.

.mentioned above, the fullers earth apparently absorbs in a selectivemanner heavy pitchlike products of the reaction, particularly the moreobjectionable of such materials such as those containing sulphur. Thefullers earth thus also assists in reducing corrosion and in reducingthe deposition of carbon or coke or heavy carbonaceous material on thewalls through whiclrheat is transmitted.

The invention is particularly applicable to the distillation of heavydistillates and residues, such as heavy gas oil from heavy crudepetroleums such as those from Mexico, California and Texas. fuel oil,reduced crude oil, and other heavy distillation residues. In thetreatment of crude petroleum oils 1n accordance with the invention, thecrude oil is stripped of light oils, particularly those such as producedby the distillation in contact with ullers earth, before the oil issubjected to the fullers earth distillation treatment. The fullers earthdistillation treatment, for example, may with advantage be ycarried outin ,conjunction with a topping process, the vresidue from the toppingprocess being supplied to the `fullers earth distillation treatment.

'In carrying out the invention, the oil vapors driven of from the heatedbody of oil in contact substantially throughout the fullers earth may besubjected to a reuxing operation, and where the heating operation iscombined with a refiuxing operation it is likewise advantageous to stripthe reflux condensate of any light oils before returning it to thefullers earth distillation treatment. The reflux condensate from suchreuxing operation, Afor example,may be returned first to a topping stillin which light oil is separated as vapor and from which thedistillat-ion residue is supplied to the fullers earth distillationtreatment.

By relieving the oil supplied to the fullers earth distillationtreatment of all light oils which vaporize rapidly at the temperature atwhich the body of oil in the ullers earth distillation treatment ismaintained, loss of heat in the still in which this operation is carriedout through vaporization of such components before these components havebeen in contact with the earth for a sufficient time to permit the earthto have had its full effect is avoided.

The invention will be further described in connection with theaccompanying drawings, illustrating in a diagrammatic and somewhatconventional manner an apparatus embodying the invention and adapted forthe practice of the process of the invention, but it is intended andwill be understood that the invention is illustrated thereby, notlimited thereto.

Referring to the drawings, the still in which the fullers earthdistillation treatment 1s carried out is shown at 11 mounted in asuitable furnace setting 12. It is advantageous to use a vertical typeof still, as illustrated, in order to provide a relatively deep bed ofearth in Contact with the oil undergoing treatment. A supporting screen13 extending entirely across the still is arranged a short distanceabove the still bottom. rIhe body of fullers earth in the still issupported by this screen and is thus kept free from the heated stillbottom. An additional supporting screen 14 may be provided at anintermediate point in this still to relieve ythe lower supporting screenof part of the weight of the earth bed. Supplementary support 17 mayalso be provided for this purpose. The body of earth in the stillextends approximately to the normal liquid level so that in operationthe surface of the body of the earth is substantially coincidental withthe oil level in the still. Manholes 15 are provided for access to thestill. Vents 1 8 extending from below the lower screen to above thenormal liquid level may be provided to prevent the formation of gas orvapor pockets below the lower supporting screen 13. A discharge outletfrom the still is shown at 19 and a level indicator at 16.

Oil is supplied to the still 11 through connection 29, arranged todischarge into the space between the still bottom and the lowersupporting screen 13. The oil is thus compelled to pass througl theearth bed before it can escape as vapor.- For better distribution,incoming oil may be introduced through a hub and spoke distributingdevice 30. Va-

pors generated in this still are conducted to the lower part of thereflux tower 2O through pipe 21. Vapors remaining uncondensed escapefrom the reflux tower through connection 22 to suitable condensing andcollecting apparatus. Reflux condensate escapes from the reflux towerthrough connection 23.

v This reflux condensate may be returned to still 11, in whole or inpart, through connection 26, but more advantageously it is subjected toa stripping operation to relieve it of all light components before beingreturned to still 11.

One suitable form of apparatus for stripping heavy oils of lightcomponents in carrying out the invention is shown in the drawing at theleft of still 11. Many form-s of apparatus may be used for this purpose.The apparatus illustrated comprises a series of stills,.1 and 2, ofordinary shell construction mounted in'suitablefurnace settings 3. Thesestills are shown in stepped relation to permit gravity flow ofunvaporized oilfrom still 1 to still 2, higher temperatures beingmaintained in still 2 in operation. While but two stills are shown inthis series,jany necessary or dcsired number may be used. In theapplication of the invention to crude oils, the number of stills in theseries may for example correspond to the number of cuts to be taken 0Ebefore the residue is subjected to the-fullers earth distillationtreatment. In the stripping apparatus illustrated, each still is shownas provided with a dephlegmator 4 through which the vapors escaping fromeach still pass on their way to suitable condensing and collectingapparatus. In the operation of the stripping apparatus illustrated,fresh oil to be treated is supplied through connection 5, provided withregulating valve 6, and the oil remaining unvaporized in still 1 flowsthrough connection 7 provided with regulating valve 8, to still 2, fromwhich oil remaining unvaporized may be supplied to the fullers earthdistillation treatment through connection 31. Still 2 is also shown asprovided with a draw off connection 9 having a .regulating valve 10. Incombined operation of the stripping stills and thefullers earth still,distillation residue from still Y2 may be withdrawn through connection31 by pump 28 and introduced into still 11 through connection 29.Additional oil, of appropriate character, may also be supplied to still11 by means of pump 28through connection 32. Reflux condensate 'to bestripped of light components, in the apparatus illustrated, is conveyedfrom the reflux tower 2O through connection 23 and trap 25, arranged toprevent vapors from still 2 entering the. reflux tower 20, andconnection 24 provided with regulating valve 33 to still 2. Directreturn of reflux condensate from the tower 20 to still 11 is providedfor through connections 26 and 27 provided with regulating valve 36.Valves 34, 35 and 37 are provided for control of the supply of heavy oilto still 11. Y

The following example of one particularly advantageous method ofoperation carried out in the apparatus shown in the drawings willillustrate-the process of the invention: Oil is supplied to still 1through connection 5 and heavy oil remaining unvaporized in still 1 isdischarged through connection 7 to still 2. The firing of stills 1 and 2is regulated and the dephlegmators 4 are controlled,- for eX- ample, tomaintain the temperature of the vapors leaving the dephlegmator on still1 at about 400 F. and the temperature of the vai tween about 575 F. and650 F. The rate of introduction of heavy oil to still 11, for exporsleaving the dephlegmator on the still 2 at about 450 F. Heavyunvaporized oil from v which the lighter components have been removed iswithdrawn from still 2 by pump 28 and introduced into still 11 betweenthe bottom of the earth bed and the bottom of the still. An oil'levelapproximating the level of the bed of earth is maintained in still 11.The firing of this still is regulated to maintain thc temperature of theoil body in the still beample` is advantageously maintained atabout 4%per hour of the normal still charge. For the direct production of agasoline character fraction, the operation of the vrefiux tower Vmay beregulated to maintain the temperature of the vapors escaping throughconnection 22,

. for example, at approximatel 400 F. In

this case, all of the reflux con ensate is with advantage returned tostill 2 from which, after removal of lighter components boiling oi belowthe temperature range through which the fullers earth is particularlyactive, the unvaporized residue from the reflux condensate is returnedto still 11.A Under these conditions, an additional yield of as much as15% to 25% of gasoline may be obtained fro the heavy oil charged tostill 11.

The temperature 'of the vapors escaping through connection 22 may bemaintained at a higher value and the vapors subsequently fractionated orcondensed and the condensate redistilled for the separat'on o a gasolinecharacter distillate. The temperature of the vapors escaping throughconnection 22, for example, may be maintained sohigh' that the refluxcondensate in tower 20 is relativelyl free from lighter componentsboiling below the' range of temperatures through which the fullers earthis particularly active, in which case the reflux condensate containingonly the heavier components of the vapors escaping from still 11 maybereturned` directly to still -11.

Although operation in accordance with the invention is not indefinitelycontinuous, the fullers earth remains active through remarkably longperiods of -time within the range of operating temperatures specified.

The `combinedbperation of the invention, in which refiuxcondensate fromthe refluxing operation towhich vapors from the fullcrs earthdistillation treatment are subject'ed is returned to a strippingoperation for the removal of light components and from which unvaporizedoil including the heavier components of such reflux condensate issupplied to the fullers earth' distillation treatment is advantageouslycarried out, as in the apparatus illustrated in the drawings, so thatthere is no substantial-loss of heat available in the reflux condensate.

The combined operation of the invention condensate from the fullersearth distilla. tion treatment and the unvaporized heavy.

oil from the ,stripping operation supplied directly to the fullers earthdistillation treatment asin the apparatus illustrated in the drawingsalso provides that the fresh oil be supplied to the earth treatment atsubstantially the temperature at which the oil body is maintained'during the earth treatment thus-greatly increasing the capacity of thelatter as well as the efficiency oi the system as a whole. i

l. An improvement in the distillation of heavy petroleum distillates andresidues for the production of gasoline therefrom, which comprisesVmaintaining a body of the heavy oil at a temperature between about 575F. and 650 F. in cont-act with a body of fullers earth substantiallycoextensive therewith, taking off vapors from said body of oil andsubjecting them to a refiuxing operation,

-taking oft' vapors including gasoline com-J ponents from the refluxingoperation', stripping reiiux condensate from the refluxing operation oflight components, and returningvreflux condensate from which lightcomponents have been so stripped to the first said body of oil.

2. An improvement in the distillation of heavy petroleum oils for theproduction of gasoline therefrom, which comprises maintaining a body ofthe heavy oil at a temperature between about 575 degrees F. and 650degrees F. in contact with a body of fullers earth substantiallycoextensive therewith,

-stripping heavy petroleum oils of light components-and supplying heavyunvaporized oil from the lstripping operation t`o maintain said oil bodywhile distilling gasoline therefrom at substantially atmosphericpressure.

3. An improvement in the distillation of heavy .petroleum oils for theproduction of gasoline therefrom, which comprises maintaining a body ofthe heavy oil at a temperature of between about 575 degrees F. and

-650 degrees F. in contact with a body ofl ALBERT E. MILLER.

